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Biomedical subjects

A Molnár

Publications and source records attributed to A Molnár.

At least 37 records · Page 2Linked to original sources
PubMed1995

Seasonal changes in sperm parameters of British milk rams.

Seasonal changes in the sperm parameters of British Milk rams were studied at weekly intervals over a period of 12 months. By comparing the seasonal averages of the test parameters, significant differences were determined in several cases. Substantial differences were found in the averages of quantitative parameters between autumn and the other seasons. As regards the qualitative parameters, the results obtained in summer and autumn were significantly different from those measured in winter and spring. The ratio of deformed spermatozoa was outstandingly high (22.72%) in August. A close negative correlation was established between sperm motility and the incidence of acrosomal defects (r = -0.52; P < 0.1%). The length of natural daylight and daily average temperature were found to exert an influence on the sperm parameters. In autumn, the combined effect of the two weather parameters shows a significant correlation with the concentration of spermatozoa (r = -0.62; P < 0.1%). As British Milk rams show well-balanced sperm production throughout the year with only minor fluctuations, they can be used for reproduction all the year round.

Animals↗
PubMed1994

Ligand-modulated cross-bridging of microtubules by phosphofructokinase.

The interaction of phosphofructokinase and microtubules results in mutual effects: decreases overall activity of the kinase and alters the ultrastructural organization of microtubules. Electron microscopic studies provide direct evidence for the periodical cross-bridges of microtubules by the kinase. 3-4 closely aligned tubules are connected by rows of highly periodic lateral arms about 13 nm long and 12 nm wide. The bundling activity of the enzyme seems to be specific since aldolase, which also interacts with microtubules, does not cross-link tubules, but it impedes the binding of the kinase to tubules. ATP, ADP and fructose bisphosphates inhibit the cross-bridges of microtubules by phosphofruktokinase to a different extent and concentration dependent manner. The kinase complexed with specific metabolites inducing distinct conformers does not interact with tubules. Microtubules cross-linked by the kinase became partly resistant to the depolymerizing action of vinblastine.

Ligands↗
PubMed1994

The Ikaros gene encodes a family of functionally diverse zinc finger DNA-binding proteins.

We previously described the lymphocyte-restricted Ikaros gene encoding a zinc finger DNA-binding protein as a potential regulator of lymphocyte commitment and differentiation. Here, we report the isolation of four additional Ikaros transcripts, products of alternate splicing that encode functionally diverse proteins. The Ikaros proteins contain unique combinations of zinc finger modules that dictate their overall sequence specificity and affinity. The Ik-1 and Ik-2 proteins can both bind, albeit with different affinities, to the same recognition sequences present in a number of lymphocyte-specific regulatory elements. The Ik-3 and the Ik-4 proteins interact only with a subset of these motifs. The Ik-1 and Ik-2 proteins can strongly stimulate transcription, whereas Ik-3 and Ik-4 are weak activators. Significantly, the transcription activation potential of the Ikaros proteins correlates with their subcellular localization. Upon ectopic expression of the Ikaros isoforms in nonlymphoid cells, Ik-1 and Ik-2 localize to the nucleus, whereas Ik-3 and Ik-4 are predominantly found in the cytoplasm. The Ikaros isoforms are expressed differentially in lymphocytes: Ik-1 and Ik-2 mRNAs are the predominating forms, and Ik-4 is present in significant amounts only in early T-cell progenitors, whereas Ik-3 and Ik-5 transcripts are expressed at relatively low levels throughout lymphocyte development. The ability of the Ikaros gene to generate functionally diverse proteins that may participate in distinct regulatory pathways substantiates its role as a master regulator during lymphocyte development.

Alternative Splicing↗
PubMed1992

[Mitochondrial myopathy (mono- and multisystem mitochondrial diseases)].

Four mitochondrial myopathy cases are reported. In addition to complaints, clinical and laboratory findings the changes in number, size, shape and in structure of the mitochondria in skeletal muscles are detailed. In three of their cases the disease is monosystemic, one case seems to be multisystemic in character: beside the morphologically proven muscle and liver changes it is likely that cardiac muscle and the central nervous system is also affected on the base of the clinical symptoms.

Adolescent↗
PubMed1991

Identification of ATGCAT sequence at sites of SmuC I restriction endonuclease by computer and physical mapping of adenovirus type 1 DNA.

Physical mapping of adenovirus type 1 DNA was carried out in order to analyze the recognition sequence of a novel Streptococcus restriction endonuclease. In addition to the new map and homology data on this poorly analyzed serotype, the result offers the definite evidence for the ATGCAT recognition sequence on adenovirus DNA and the physical map of cleavage points.

Adenoviridae↗
PubMed1989

[Experimental gerontology and the reliability theory].

The reliability theory was elaborated for the estimation of the reliable action of technical systems. When it is applied to biological systems, it is important to characterize unequivocally the disorder which will substantially after the reliable activity of the entire organism or of individual systems. The authors investigated in their experiments during the postnatal development of rats changes in the erythrocyte stability. The age-conditioned decline was evaluated as a disorder. The erythrocyte stability was assessed in animals of different age, i. e. in 4-, 6-, 10-, 18- and 24-month-old animals by the method of the haemolytical action of brilliant cresyl blue in isotonic NaCl solution. The results of experiments suggest that when red cells were incubated in isotonic NaCl solution only, there was no difference in the lysis of erythrocytes in different age groups. However, when they were incubated in isotonic NaCl with brilliant cresyl blue, there was a significantly greater haemolysis in red cells of 4-, 18- and 24-month-old rats, as compared with the lysis of red cells from 6- and 10-month-old animals. Red cell lysis conditioned by brilliant cresyl blue in relation to age is discussed from the aspect of the reliability theory.

Aging↗
PubMed1989

[Aspects of social and health problems in the aged in the Kosice-Nové Mesto District].

The author presents the results of repeated examinations of a group of 725 old people on the records of the geriatric welfare centre of the district Kosice-Nové mesto. Attention is paid to medico-social needs of old people, their demands, to the extent and quality of care and housing conditions. Some suggestions are presented for the health and social services.

Aged↗
PubMed1989

[The development and beginnings of otorhinolaryngology at the Comenius University Medical School in Bratislava].

The subject of the paper is the history of development and the beginnings of otolaryngology at the Medical Faculty, Comenius University in Bratislava. A special feature of the process was that in Bratislava two separate clinics were established: an otological and rhinolaryngological clinic. The founder and first head of the otological clinic founded in 1932 was professor MUDr. Pavel Záviska and the first head of the rhinolaryngological clinic was professor MUDr. Bedrich Wiskovský. At the end of 1938 the two departments fused and professor Wiskovský was the head of the new department.

Czechoslovakia↗
PubMed1987

Preparation, characterization, and potential application of an immobilized glucose oxidase.

A simple, one-step process, using 0.25 M p-benzoquinone dissolved in 20% dioxane at 50 degrees C for 24 h was applied to the activation of polyacrylamide beads. The activated beads were reacted with glucose oxidase isolated from Aspergillus niger. The coupling reaction was performed in 0.1 M potassium phosphate at pH 8.5 and 0-4 degrees C for 24 h. The protein concentration was 50 mg/mL. In such conditions, the highest activity achieved was about 100 U/g solid. The optimum pH for the catalytic activity was shifted by about 1 pH unit in the acidic direction to pH 5.5. Between 35 and 50 degrees C, the activity of the immobilized form depends on the temperature to a smaller extent than that of the soluble form. Above 50 degrees C, the activity of immobilized glucose oxidase shows a sharper heat dependence. The enzyme-substrate interaction was not profoundly altered by the immobilization of the enzyme. The heat resistance of the immobilized enzyme was enhanced. The immobilized glucose oxidase is most stable at pH 5.5. The practical use of the immobilized glucose oxidase was tested in preliminary experiments for determination of the glucose concentration in blood sera.

Catalysis↗
PubMed1987

Elimination of non-specific nucleases from restriction endonuclease preparations by different binding on free DNA ligand.

In the purification of a novel restriction endonuclease (an AvaIII isoschizomer, isolated in this laboratory) standard methods were insufficient to eliminate non-specific nuclease contaminations. Taking advantage of the specific site recognition and binding of the restriction endonuclease on DNAs, a method is described for the simple extraction of non-specific nucleases. DNA substrates without recognizable sites do not bind the restriction endonuclease, while non-specific nucleases are absorbed to, and eliminated with, the DNA via gel filtration chromatography under special conditions.

Binding, Competitive↗
PubMed1985

Comparison of antioxidant red blood cell enzymes in premature and full-term neonates.

Earlier investigations extended exclusively to comparisons of the red blood cells (RBC) Cu,Zn-superoxide dismutase in neonates of various ages. We have now carried out comparative measurements on the activities of RBC catalase and glutathione peroxidase from the same source. Besides the enzymes, we also measured the lipid peroxidation (LP). The differences between the RBC of premature and full-term neonates were found to be significant. The lower antioxidant enzymatic activity and LP level in premature infants are explained by the immaturity of the biochemical systems and the different lipid composition of the RBC membranes.

Catalase↗
PubMed1985

Riboflavin (vitamin B2) treatment of neonatal pathological jaundice.

The effect of traditional blue-light and riboflavin combined with blue-light was compared in newborns affected by ABO incompatibility, admitted for exchange transfusion. During the period of preparation for the intervention 14 patients were treated with blue light alone and 14 patients with riboflavin combined with phototherapy. A single dose of 10 mg/kg riboflavin was administered intravenously. The duration of treatment was three hours in both groups. The effect of phototherapy was markedly enhanced by the additional riboflavin, by the end of the 3-hour period a significant fall of serum bilirubin was demonstrated in the 14 patients treated with blue light and riboflavin while in the patients treated with phototherapy alone the bilirubin level continued to rise. There was no difference in the activity of the antioxidant enzymes superoxide dismutase and catalase, and in lipid peroxidation between the groups.

ABO Blood-Group System↗
PubMed1983

In vitro proliferation of normal and leukaemic human leukocytes controlled by an inhibitory endopeptide.

GI-3, an endogenous inhibitory fraction isolated from leukocytes, selectively inhibits the proliferation of granuloid precursor cells in a non-toxic manner. Its active principle was determined as an acidic chlor-tolidine positive decapeptide [ 3 ]. The in vitro effect on normal and acute leukaemic human bone marrow and blood cells was examined. A dose dependent inhibition by GI-3 of 3H-TdR incorporation into myeloid cells of normal bone marrow was found, the sensitivity of human cells being higher than that of rat cells. The proliferation of the target leukaemic bone marrow and blood cells (AML, AMMoL) was also decreased by the endogenous inhibitor in a dose dependent manner in untreated subjects as well as in patients in remission or relapse. The rate of inhibition of leukaemic of well-known cytostatics (adriamycin hydrochloride, dianhydrogalactitol) applied for comparison. Beyond its direct cytostatic effect, GI-3 could be used in the differential diagnosis of blastic leukaemias, complementing the routine cytochemical methods.

Adult↗